Ship&#39;s log and speed indicator



Aug. 27, 1929.

S. SHIMIZU SHI-PS LOG AND SPEED INDICATOR Filed Oct. 5, 1822 5 I S m xa rolx BY I Z OATTORNEK Patented Aug. 27, 1929.

UNITED STATES PATENT OFFICE.

SEIZO SHIMIZU, 0F HONGO-KU, TOKYO, JAPAN.

SHIPS LOG AND SPEED INDICATOR.

Application filed October 5, 1922, Serial No. 592,476, and in Japan August 10, 1922.

This invention relates to a ships log, and especially to a speed indicator for marine vessels which is simple in construction and more eflicient at all speeds than devices of this class heretofore employed.

The main object of the invention is the provision of a device of this class specified embodying a closed container containing mercury upon which a hollow float is operated by means of a differential of pressures exerted thereon by movement of a coacting member through the water at diiferent speeds, said hollow float being caused to rise under such pressures to a height proportional to the square root of such pressures, or difference of pressures on the inside and outside of the float, as will be explained more fully hereinafter. In connection therewith I employ electrical indicating means responsive to the movements of said float, the resultant varying current affording an indication of the ships speed at any time, and also serving to record the distance traveled by the ship, the speed and distance indications being provided without resorting to the use of a clock, as has heretofore been the case.

With these objects in view the invention consists of a construction and combination of parts of which a preferred embodiment is illustrated in the accompanying drawing, in which Figure 1 is an elevation, with parts in section, of my invention, and includes a diagrammatical showing of an electrical indicating means forming part of the device, and

Fig. 2 is an enlarged detail view of the pilot tube.

Fig. 3 is an enlarged view of a guide tube fitted to the pilot tube.

In the embodiment of my invention shown herein, both the static and the kinetic pressures of the sea-water without the ship are transmitted toan apparatus, designated generally by A, constructed preferably of metal or glass and located within the vessel, by a pilot-tube Q, projecting into the water under said ship and communicating with the main portion A of the apparatus, said pilot-tube being located as near as possible to the turning centre of the ship. With such an apparatus both the static and kinetic pressures of the water are transmitted, by air contained in a fluid path forming part of the apparatus A, to exert pressures of vary ing force on a float C adapted to be sustained in a closed mercury container B, to cause the float C to rise and fall in said container in unison with such varying pressures.

The pilot tube Q, is divided into two parts or passages by a partition wall N shown in Fig. 2, and the openings A and A are in communication with the lower ends of the passages P and P respectively.

When the vessel is moving in a direction indicated by the double arrows in Fig. 2, a kinetic pressure of the sea water is admitted into the forward opening A and a hydro static pressure into the opening A the latter being due to the depth of the sea water at that point. The opening A is positioned at a right angle to the opening A These respective pressures are transmitted to air chambers R and R shown in Fig. 1, through the passages P and P the valves E, F, G and H being open and valves I and J closed. The water may be forced into the air chambers, partially filling the same and creating an air pressure therein. This air pressure in the air chambers R and R is transmitted to the inside and outside of the float C (Fig. 1) through pipes P and P The float C is constructed according to the Dines principle, of Matl'iematische Untersuchung und Vebesserung d-er l/Vindldruckregistrier-Apparate System Dines by von Auer v. Buky, and described in Physikalische Zeitschrift, 10 Jahrgung, No. 25, 1909, p. 1008.

According to this Dines principle, where there is a differential in pressures on the inside and outside of a hollow float, the float will beraised an amount proportional to the square root of the difference of pressures on the inside and outside of the float. I11 the presentapparatus, as this difference in pressures is caused by the movement of the vessel through the water, the amount of rise of the float C is an indication of the speed of the vessel.

If the level of the sea water in the air chambers R or R becomes too high, through leakage or otherwise, the four valves, E, F, G and H, are closed; Air is then forced into the air chambers through the valve H by attaching an air pump thereto and a part of the water allowed to escape by opening the valve H Thus the level of the water in the air chambers may be adjusted to the desired height for correct operation. Valves I and J are opened in this operation.

To correct the position of the float C, the pressures inside and outside the float are equalized by closing the valves G and II and opening the valves E, F, I and J. The float will then come to the normal or Zero posi tion or, if not, it may be corrected by adding or taking out mercury through the valve K.

In Fig. 3, is shown a guide or casing P which is fitted to the bottom of the vessel and through which the pilot tube Q may be inserted and fixed therein. The valve D is provided to prevent the sea water from flowing in when the pilot tube is removed. This provides a convenient means for removably mounting the device in the vessel.

A concentric cylindrical lining I*F of reduced diameter is provided within the easing B, this construction serving to permit the use of the minimum amount of mercury in the container.

At the upper end of the float C a rigid electrically insulated rod E is shown, and secured to the upper end of said rod is a metallic contact I adapted for contact with a resistance S. When no difference of pressure exists between the inside and the outside of the float the contact I will be at the lower end of the resistance S. Electrically operated means, controlled by the position of the float C, shown diagrammatically at the top of Fig. 1, are provided, by which both the speed of the ship and the distance traveled thereby may be indicated.

A case J of cylindrical form is shown as attached to the container B in such a manner as to exclude external air pressure. V indicates a main source of current, see Fig. 1, and for the purpose of securing a definite electric current a resistance like that of a Nernst lamp or a high resistance W is inserted in its circuit. At M is shown a milliammeter adapted to indicate differences of current and consequent differences in the ships speed upon the rise and fall of the float C in the container B. An ampere-hour meter R is connected in series to the milliammeter M. Direct reading is afforded by making the ampere-hour meter capable of indicating the distance traveled by the ship.

At K I have shown a change-over switch, connected ordinarily with the terminal 1, for regulating the current by adjustment of a resistance W, to give a definite deflection to the milliammeter by turning the switch K to the terminal 2 when the source of electric current is varied.

What I claim is:

1. A device of the class described, comprising an elongated member adapted to have one end inserted through an opening in the hull of a ship and into the water outside,

said member being provided with two separate longitudinal passages, one having at one end a lateral opening intended to face in the normal direction of motion of the ship and the other having a similar opening substantially at right angles to the one first named, both openings being intended to be outside the ship, conduits communicating with said passages respectively for conducting water therefrom, closed chambers with which said conduits respectively communicate so as to supply water thereto under pressure, said chambers adapted to have air therein under pressure above the water, an upright elongated closed chamber containing a quantity of mercury and also a vertically elongated hollow float. open at its lower end, two conduits respectively communicating with the air spaces of the two chambers first named and one opening into the elongated chamber above the mercury therein and the other extending into said chamber through its lower end and opening into the hollow of the float for supplying air thereinto tending to lift the float, the air supplied from the other conduit tending to force the float down.

2. A device of the class described, comprising an elongated member adapted to have one end inserted through an opening in the hull of a ship and into the water outside, said member being provided with two separate longitudinal passages, one having at one end a lateral opening intended to face in the normal direction of motion of the ship and the other having a similar opening substantially at right angles to the one first named, both openings being intended to be outside the ship, conduits communicating with said passages respectively for conducting water therefrom, closed chambers with which said conduits respectively communicate so as to supply water thereto under pressure, said chambers adapted to have air therein under pressure above the water, an upright elongated closed chamber containing a quantity of mercury and also a vertically elongated hollow float open at its lower end, two conduits respectively communicating with the air spaces of the two chambers first named and one opening into the elongated chamber above the mercury therein and the other extending into said chamber through its lower end and opening into the hollow of the float for supplying air thereinto tending to lift the float, the air supplied from the other conduit entering the chamber above the float tending to force the float down, and valves in the said air and water conduits for adjusting the pressures in said chambers.

In testimony whereof, I afiix my signature.

SEIZO SHIMIZU. 

